EFFECT OF PLUG REMOVAL ON LOAD TRANSFER IN PLUGGED OPEN ENDED PILE BEHAVIOR

The experimental tests contain 36 tests carried out on single piles. All tubular piles tested by using the poorly graded sand from the southern city of Karbala in Iraq. The sand was prepared at three different densities using a raining technique. Different parameters are considered such as method of installation, relative density, removal of soil plug with respect to length of plug and pile length to diameter ratio. To simulate the pile load test in the field, the driving and pressing system for pile installation were manufactured. Strain gauges are used to separate skin friction with two components from and resistance bearing. The soil plug is removed by using a new device which is manufactured to remove the soil column inside open pipe piles group during driven and pressed device. The principle of soil plug removal depends on suction of sand inside pile. It was concluded that the removal of soil plug from piles will cause a reduction in pile load carrying capacity due to elimination of two components, internal friction and the confining in end bearing zone. The maximum reduction occurred in the dense state of soil with as a percentage of about 61.5%. The sand column length increases with the progressing of the installation pressure when pressing method is used, but in driven piles, there is no systematic trend of the sand column length generated in the piles. Long of piles have a higher probability of plugging and plugging penchant is also higher in dense and dilatant soils.